1. Technical Field
The present disclosure relates to a semiconductor laser device.
2. Discussion of the Related Art
There has been known a semiconductor laser device in which a “heat sink” (corresponds to a “mounting member” in the present specification) having a “semiconductor laser element” mounted thereon is engaged in a through portion defined in a “stem” (corresponds to a “base member” in the present specification, as in JP H06-302912A). In JP H06-302912A, exposing the “heat sink” on a backside of the “stem” allows direct connection of the “heat sink” to an “external heat sink”, which enables an improvement in its heat dissipation properties (see paragraph 10 of JP H06-302912A).
However, it is practically difficult to connect the lowermost surface of a mounting member and the lowermost surface of a substrate so as to be in the same plane. The mounting member and the substrate are connected with one another by using a solder material and applying heat, but due to a difference in the coefficient of thermal expansion between the mounting member and the substrate, the lowermost surface of the mounting member and the lowermost surface of the substrate tend to be on different planes. For this reason, although obtaining excellent heat dissipation is possible if the lowermost surface of the mounting member and the lowermost surface of the substrate can be arranged on the same plane, the heat dissipating properties significantly drops if the lowermost surfaces of both do not share the same plane. Thus, there has been a problem in which stable heat dissipating properties are difficult to obtain.